Embodiments presented herein generally relate to electric machines, and more particularly to apparatuses for cooling electric machines.
Rotating electric machines, such as generators and motors, conventionally employ a rotor section, which rotates and includes one or more (electro- or permanent) magnet assemblies, and a stator section, which often surrounds the rotor section and includes a series of conductive windings. Depending on whether the electric machine is a generator or a motor, electric current in the conductive windings will either be induced by or cause rotation of the rotor section. In either case, due to the current in the stator windings and the resistance thereof, thermal energy will be produced, with the amount of thermal energy generated in the stator section being roughly proportional to the amount of power an electric machine generates (for generator application) or delivers (for power motor application). For high power density rotating electric machines, if the thermal energy is not sufficiently removed, the temperature in the stator section can exceed the material limits electrical insulation and/or other materials within the stator section.
In advanced electric machine applications, the demand for power has been constantly increasing while the desirable machine size has been constantly decreasing. An electrical machine that meets these two conditions generally has high power density and very demanding cooling requirements.